'Work," said the Victorian social commentator Thomas Carlyle, "is the grand cure of all the maladies and miseries that ever beset mankind." I think he had a point, especially in relation to crime and recidivism.

I was reminded of Carlyle's words when I read justice minister Ken Clarke's speech yesterday to the Centre of Crime and Justice Studies in London. In direct contrast to his colleague Michael Howard's "Prison Works" philosophy, which Howard vigorously promoted when he was home secretary from 1993 until 1997, Clarke is now championing what his party calls a "rehabilitation revolution". He said that, under his leadership, prisons are going to be places of "education, hard work and change".

Clarke's stated priority is to protect the public – and rightly so. But he knows in his heart that just banging more people up and for longer, in prisons that have become little more than human warehouses, doesn't really help reduce the number of potential victims. Contrary to what his predecessor Jack Straw told the Daily Mail yesterday, there is not a shred of evidence that more people in prison leads to a significant drop in crime levels. What is proven, however, is that the fewer constructive opportunities to which people in prison have access, the more likely they are to reoffend after release.

My first inkling that Clarke might be a "progressive" came 18 years ago, when he handed an associate of mine a £5 note and wished him "good luck". Clarke had just taken over as home secretary, and had decided to visit his constituency prison in Nottingham. Like my associate and the half-dozen other prisoners present, I was serving life for murder. Those of us who met Clarke that day were in the process of organising a charity marathon run around the prison exercise yard, and my associate had asked Clarke for a donation. We were impressed that he didn't hesitate for a moment.

The jail was a grimy Victorian blast from the past that had a lively dog-eat-dog landing culture and was in dire need of modernisation. But what it had going for it was its mature commitment to education and a broad programme of work-related skill building, in construction, industrial cleaning and electronics. People who survived the stresses and strains of the wing could leave the prison rewarded for their efforts in the workshops with qualifications that would give them a starting chance in the job market.

Pertinently, the reoffending rate among released prisoners in 1992 was roughly 50% over two years. When Howard took over from Clarke and sent the national prison population soaring, the training and education facilities virtually disappeared from Nottingham prison – a microcosm of what was happening in prisons across the country. It is no coincidence that at the same time, the reoffending rate also began to rise. Since New Labour took over in 1997, there has been no let-up in the "prison works" rhetoric, and no let-up in the rise in rate of reoffending, which currently stands at around 70%.

Clarke says he wants to work in partnership with the voluntary and private sectors to "rehouse, rehabilitate and find work for released prisoners, with bodies only paid if their efforts lead to a significant fall in reoffending". This is wonderful news, and I would like to recommend one such body that has an unassailable track record.

Blue Sky Development & Regeneration, a not-for-profit company that gives paid work to people coming out of prison and helps them move into long-term employment, recently won the award for Social Care and Welfare at the national Charity Awards. And no wonder. In the five years since it was set up, Blue Sky has provided employment for nearly 300 ex-offenders, the population of an average regional prison. Every Blue Sky team member is offered training for when they eventually leave the company, in literacy and numeracy, construction work or environmental management. And guess what? The reoffending rate for former Blue Sky workers is just 15%.

As David Cameron told the House of Commons when he defended his justice minister's speech, "Prison can work." But only if it is used constructively – by ensuring it provides sufficient education, skills training and good, hard work. I think Ken Clarke's refreshing honesty would have impressed Thomas Carlyle.